Since the calibration accuracy decreases with the reduction of irradiance power,the nonlinearity of sensitivity is experimentally investigated and corrected in order to improve the precision of calibration for Solar I...Since the calibration accuracy decreases with the reduction of irradiance power,the nonlinearity of sensitivity is experimentally investigated and corrected in order to improve the precision of calibration for Solar Irradiance Absolute Radiometer( SIAR). The optimization method is proposed based on the interpolation approximation principle. The real-time correction sensitivities are repeatedly measured at each radiant power.The relative system error of sensitivity nonlinearity is 2.2%. The impact of sensitivity nonlinearity is analyzed.The radiant powers are measured by the optimization method and the traditional method. The comparison experiment results illustrate that the optimization method improves the measure accuracy to 0. 1%. The sensitivity nonlinearity is compensated by the real-time correction. Thus,the optimization method significantly improves the calibration precision of ground-based comparison experiment. The investigation of sensitivity nonlinearity also provides the theoretical and experimental basis for optimizing the on-orbit calibration precision of Total Solar Irradiance Monitor( TSIM).展开更多
Accurate measurements of broadband outdoor longwave irradiance are important for renewable energy applications and the study of the atmosphere and climate change. A unique method of pyrgeometer calibration has been de...Accurate measurements of broadband outdoor longwave irradiance are important for renewable energy applications and the study of the atmosphere and climate change. A unique method of pyrgeometer calibration has been developed to improve the measurement uncertainty [1]. The results of this method yielded irradiance values within ±3 W/m<sup>2</sup> of those traceable to the World InfraRed Standard Group (WISG). This article describes a technique for validating this pyrgeometer calibration method using two Absolute Cavity Pyrgeometers (ACPs). The ACPs and pyrgeometer model PIR were deployed outdoors and the irradiance measured by the PIR was compared against the average irradiance measured by the two ACPs. The irradiance measured by the PIR was calculated using two equations, NREL equation and the Physikalisch Meteorologisches Observatorium Davos (PMOD) equation. The uncertainty with 95% confidence level (<em>U</em><sub>95</sub>) of the irradiance measured by the PIR using NREL equation equaled ±3.51 W/m<sup>2</sup> with respect to SI and using PMOD equation <em>U</em><sub>95</sub> equaled ±2.99 W/m<sup>2</sup> with respect to SI. These results suggest that the PIR calibration method might be useful in addressing the international need for a secondary standard pyrgeometer traceable to SI.展开更多
We experimentally evaluate and correct the non-equivalence between electrical and radiative heating of solar irradiance absolute radiometer to compensate the systematic error of radiant power measurement at ambient pr...We experimentally evaluate and correct the non-equivalence between electrical and radiative heating of solar irradiance absolute radiometer to compensate the systematic error of radiant power measurement at ambient pressure. A relative difference of the order of 0.08%-0.27% between electrical and radiative heating sensitivities is shown, and the resulting non-equivalence correction factor is calculated. The radiant power measurement equation is modified using the non-equivalence correction factor, a systematic deviation of 0.19% of radiant power measurement is hence eliminated.展开更多
基金Sponsored by the National Natural Science Foundation of China(Grant Nos.41227003 and 41474161)
文摘Since the calibration accuracy decreases with the reduction of irradiance power,the nonlinearity of sensitivity is experimentally investigated and corrected in order to improve the precision of calibration for Solar Irradiance Absolute Radiometer( SIAR). The optimization method is proposed based on the interpolation approximation principle. The real-time correction sensitivities are repeatedly measured at each radiant power.The relative system error of sensitivity nonlinearity is 2.2%. The impact of sensitivity nonlinearity is analyzed.The radiant powers are measured by the optimization method and the traditional method. The comparison experiment results illustrate that the optimization method improves the measure accuracy to 0. 1%. The sensitivity nonlinearity is compensated by the real-time correction. Thus,the optimization method significantly improves the calibration precision of ground-based comparison experiment. The investigation of sensitivity nonlinearity also provides the theoretical and experimental basis for optimizing the on-orbit calibration precision of Total Solar Irradiance Monitor( TSIM).
文摘Accurate measurements of broadband outdoor longwave irradiance are important for renewable energy applications and the study of the atmosphere and climate change. A unique method of pyrgeometer calibration has been developed to improve the measurement uncertainty [1]. The results of this method yielded irradiance values within ±3 W/m<sup>2</sup> of those traceable to the World InfraRed Standard Group (WISG). This article describes a technique for validating this pyrgeometer calibration method using two Absolute Cavity Pyrgeometers (ACPs). The ACPs and pyrgeometer model PIR were deployed outdoors and the irradiance measured by the PIR was compared against the average irradiance measured by the two ACPs. The irradiance measured by the PIR was calculated using two equations, NREL equation and the Physikalisch Meteorologisches Observatorium Davos (PMOD) equation. The uncertainty with 95% confidence level (<em>U</em><sub>95</sub>) of the irradiance measured by the PIR using NREL equation equaled ±3.51 W/m<sup>2</sup> with respect to SI and using PMOD equation <em>U</em><sub>95</sub> equaled ±2.99 W/m<sup>2</sup> with respect to SI. These results suggest that the PIR calibration method might be useful in addressing the international need for a secondary standard pyrgeometer traceable to SI.
基金supported by the National Natural Science Foundation of China under Grant No.41227003
文摘We experimentally evaluate and correct the non-equivalence between electrical and radiative heating of solar irradiance absolute radiometer to compensate the systematic error of radiant power measurement at ambient pressure. A relative difference of the order of 0.08%-0.27% between electrical and radiative heating sensitivities is shown, and the resulting non-equivalence correction factor is calculated. The radiant power measurement equation is modified using the non-equivalence correction factor, a systematic deviation of 0.19% of radiant power measurement is hence eliminated.
